Adding external library into Qt Creator project

Question

How can I add external library into a project built by Qt Creator RC1  version 0 9 2   For example  the win32 function EnumProcesses   requires Psapi lib to be added in the project to build

User · Answer

Are you using qmake projects  If so  you can add an external library using the LIBS variable  E g   win32 LIBS    path to Psapi lib

User · Answer

If you want to deploy your application on machines of customers  rather than using your application only yourself  we find that the LIBS   -Lxxx -lyyy method can lead to confusion if not problems   We develop applications for Linux  Mac and Windows using Qt  We ship complete  stand-alone applications  So all non-system libraries should be included in the deployment package  We want our customers to be able to run the application from the same USB stick for all OSs  For reasons of platform compatibility the USB stick must then be formatted as FAT32  which does not support  Linux  symlinks   We found the LIBS   -Lxxx -lyyy idiom too much of a black box    We do not exactly know what the filepath is of the  static or dynamic  library that has been found by the linker  This is inconvenient  Our Mac linker regularly found libs different from the ones we thought that should be used  This happened several times with OpenSSL libraries where the Mac linker found and used its own - older  incompatible - OpenSSL version rather than our requested version  We cannot afford that the linker uses symlinks to libraries as this would break the deployment package  We want to see from the name of the library whether we link a static or a dynamic library    So for our particular case we use only absolute filepaths and check whether they exist  We remove all symlinks   First we find out what operating system we are using and put this in the CONFIG variable  And  for instance for Linux 64bit  then   linux64       LIBSSL    OPENSSLPATH linux64 lib libssl a      exists   LIBSSL   error   Not existing   LIBSSL       LIBS     LIBSSL     LIBCRYPTO    OPENSSLPATH linux64 lib libcrypto a      exists   LIBCRYPTO   error   Not existing   LIBCRYPTO       LIBS     LIBCRYPTO     All the dependencies can be copied into deployment package as we know their filepaths

User · Answer

LIBS    C  Program Files OpenCV lib   won t work because you re using white-spaces in Program Files  In this case you have to add quotes  so the result will look like this  LIBS     C  Program Files OpenCV lib   I recommend placing libraries in non white-space locations  -

User · Answer

The error you mean is due to missing additional include path  Try adding it with  INCLUDEPATH    C  path to include files  Hope it works  Regards

User · Answer

I would like to add for the sake of completeness that you can also add just the LIBRARY PATH where it will look for a dependent library  which may not be directly referenced in your code but a library you use may need it    For comparison  this would correspond to what LIBPATH environment does but its kind of obscure in Qt Creator and not well documented   The way i came around this is following   LIBS    -L    PRO FILE PWD  Path to Psapi lib     Essentially if you don t provide the actual library name  it adds the path to where it will search dependent libraries  The difference in syntax is small but this is very useful to supply just the PATH where to look for dependent libraries  It sometime is just a pain to supply each path individual library where you know they are all in certain folder and Qt Creator will pick them up

User · Answer

And to add multiple library files you can write as below      INCLUDEPATH    E  DebugLibrary VTK E  DebugLibrary VTK Common   E  DebugLibrary VTK Filtering E  DebugLibrary VTK GenericFiltering   E  DebugLibrary VTK Graphics E  DebugLibrary VTK GUISupport Qt   E  DebugLibrary VTK Hybrid E  DebugLibrary VTK Imaging   E  DebugLibrary VTK IO E  DebugLibrary VTK Parallel   E  DebugLibrary VTK Rendering E  DebugLibrary VTK Utilities   E  DebugLibrary VTK VolumeRendering E  DebugLibrary VTK Widgets   E  DebugLibrary VTK Wrapping        LIBS       -LE  DebugLibrary VTKBin bin release -lvtkCommon -lvtksys   -lQVTK -lvtkWidgets -lvtkRendering -lvtkGraphics -lvtkImaging -lvtkIO -lvtkFiltering -lvtkDICOMParser -lvtkpng -lvtktiff -lvtkzlib -lvtkjpeg -lvtkexpat -lvtkNetCDF  -lvtkexoIIc -lvtkftgl -lvtkfreetype -lvtkHybrid -lvtkVolumeRendering -lQVTKWidgetPlugin -lvtkGenericFiltering

User · Answer

The proper way to do this is like this   LIBS    -L path to -lpsapi   This way it will work on all platforms supported by Qt  The idea is that you have to separate the directory from the library name  without the extension and without any  lib  prefix   Of course  if you are including a Windows specific lib  this really doesn t matter   In case you want to store your lib files in the project directory  you can reference them with the    PRO FILE PWD  variable  e g    LIBS    -L    PRO FILE PWD  3rdparty libs   -lpsapi

User · Answer

in  pro   LIBS    Ole32 lib OleAut32 lib Psapi lib advapi32 lib  in  h  cpp   pragma comment lib  user32 lib     pragma comment lib  psapi lib

[c++] Adding external library into Qt Creator project

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